Expression of concern regarding paper by Park et al, published on 25 June 2015: “Epidemiological investigation of MERS-CoV spread in a single hospital in South Korea, May to June 2015”, Euro Surveill. 2015;20(25):pii=21169.
It has been brought to our attention that some of the authors may not have been informed about the content of the above paper. There is a lack of clarity regarding rights to use the data.
The editorial team are investigating what action needs to be taken.

A recent paper by Rekart and colleagues (1) presented the
findings of a mass treatment intervention to eliminate an outbreak of syphilis
in Vancouver, British Columbia. Following several years of very low reported
infectious syphilis rates in British Columbia (less than 0.5 per 100 000
population) (2), with the majority of cases acquired overseas, there was a
marked increase in numbers of reported cases from mid-1997 onwards. This was
largely due to a geographically localised outbreak in Vancouver's
disadvantaged downtown eastside area, with rates reaching 126 per 100 000 in
this area in 1999. Sixty five percent of the 277 cases reported were among
persons who had contact with a potential source of their infection in or from
this area. The outbreak was spread mainly through heterosexual contact, with
42% of patients associated with the sex industry (18% sex workers and 24%
clients, (2)). Only 6% of cases were in men who have sex with men (MSM). Given
high HIV rates among among injection drug users (IDUs) in Vancouver, and the
frequent involvement of female IDUs involved in sex work, rising syphilis
incidence could facilitate the spread of HIV infection both within the
disadvantaged population of Vancouver's downtown eastside itself, as well as
outwards from sex workers through clients into the general population (2).

Traditional public health control measures, which included contact tracing,
screening, public education, and condom distribution, had failed to control
the outbreak. A targeted mass treatment initiative, involving administration
of a single oral dose of azithromycin to people at high risk of infection in
the downtown eastside, was implemented in January and February 2000. This
strategy was adopted because of the geographical concentration of the at risk
population, and the availability of a single dose oral treatment, 1.8g
azithromycin. The latter has a long serum half life (68 h), and in recent
trials has proved as effective as benzathine benzylpenicillin for treatment of
incubating syphilis (3).

Sex workers, their clients, and people reporting recent (unprotected)
casual sexual contact, were recruited from the downtown eastside and adjacent
municipalities. Treatment doses and information were also given to
participants to pass on to otherwise inaccessible peers and sexual contacts, a
technique known as secondary carry. The intervention reached 2981 (8.1%)
residents aged 15-49 years in the downtown eastside area, and 1055 of the
estimated 1300-2600 sex workers in Vancouver. The proportion of clients of sex
workers reached is unknown. In order to obtain maximum intervention coverage,
no specimens were taken, so it is not known how many of the people who took
treatment actually had syphilis.

Following the intervention, there was a significant fall in the mean number
of reported syphilis cases from February to July 2000 (monthly mean 6.7 cf
10.2 pre-intervention). Reported syphilis rates returned to pre-intervention
rates in September 2000, however, and in 2001 more cases were reported than in
1999.

Results of two previous, smaller, mass treatment interventions in
heterosexual groups in North America also showed successful results after 6
months of follow up (4, 5). Such short term decreases in syphilis incidence
may not be sustainable, however, and may even have negative consequences on
postintervention syphilis incidence rates. Rekart and colleagues caution
against the implementation of mass treatment interventions for syphilis, and
state that the lack of a sustained effect of the intervention is likely to be
due to a failure to reach and treat high enough proportions of the
marginalised and inaccessible sections of the target population (1). Targeted
mass treatment may have increased the pool of susceptible, high risk
individuals who were subsequently exposed to infectious syphilis by those
people who were not reached by the intervention.

A number of countries in western Europe have recently experienced localised
outbreaks of syphilis (6, 7, and references therein). Mass treatment would not,
however, be an appropriate and effective intervention in this context, because
the majority of outbreaks have predominantly involved MSM who have attended
social venues such as saunas and clubs, and who are not geographically and
demographically localised in the same way as the Vancouver outbreak.

Nevertheless, the Vancouver study is a good example of the use of community
and peer outreach as a means of accessing marginalized, 'hard to reach' groups
at high risk of HIV/STI infection. The syphilis outbreaks in both Vancouver
and Europe challenge traditional public health approaches to STI control,
particularly in terms of contact tracing and treatment. In Vancouver, 46% of
index syphilis cases were unable or unwilling to name their sexual contacts
(2); similarly, in the United Kingdom, high proportions of MSM who have
syphilis are unable to name their sexual contacts. Innovative approaches such
as targeted peer outreach combined with non-invasive sampling techniques such
as saliva collection, could aid case detection and prompt treatment of
infected individuals. Social network methods (8) could also be useful to
augment traditional sexual contact tracing procedures. In addition, syphilis
screening should be offered to all pregnant women as a matter of course in
Europe, in order to prevent congenital transmission (9).

Finally, it should be noted that the conclusions drawn from the Vancouver
intervention are not necessarily applicable to developing countries,
particularly in sub-Saharan Africa, where extremely high HIV and STI incidence
rates in the core group of sex workers, coupled with lack of access to
appropriate healthcare and STI diagnostic facilities, may in some contexts
justify administration of rounds of mass treatment for STIs at very regular
intervals. Such an approach was implemented in a South African mining
community, where a directly observed 1g dose of azithromycin was given every
month to sex workers attending a mobile clinic. This resulted in significant
declines in the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae,
and clinically observed genital ulcer disease in sex workers. Decreased rates
of symptomatic STIs were also observed in the client group of miners in the
intervention area (10).

Twenty places are available for the above meeting to be held at the
Communicable Disease Surveillance Centre (Colindale, London, UK). If you would
like to attend please contact Maria Solomou (tel: 020 8200 6868 ext 4574 email:
msolomou@phls.org.uk). There is no
conference fee but attendees will have to meet their own travel expenses.